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By Rachel Bauer, Jacob Henderson, Dr. Catherine Johnson

Capital Quarries in Owensville, Missouri faces several challenges when designing a blast that allows for ease of movement while maintaining controlled throw and compliant air over pressure. The primary challenge is the nearest non-owned structure (NNOS) is a residential home located 250 feet from the quarry. Another challenge is a production bench which is 100 feet tall and separated from the NNOS by Pennsylvanian fire clay that filters out high frequency waves from the blast. Material from the blast must also be less than 5 inches in order to be processed by the crusher in the quarry. To provide as much relief as possible, production shots will consist of a single row with the minimum required burden. To design the shot, signature hole analysis was used to determine the optimal timing between powder columns. Electronic detonators provided an accurately timed shot to minimize the amplitude of the vibrations while maximizing the frequencies. Boretraking and 3D profiling with Renishaw laser profiler and Strayos drone photogrammetry provided an accurate burden measurement. Powder factor was kept at 1.3 tons/lb using bulk emulsion. The boreholes were split into 5 powder columns with the top of the hole firing first in order to blast to floor grade. The resulting shot produced good fragmentation and shot to floor grade. Seismograph readings showed air over pressure vibrations within legal limits. Due to this success, multiple shots will be designed using the process described.

Feb 6, 2023

By Anne Caroline Costacurta Polli, Jose Rojas Cáceres, Roberto Mahler de Morais, Thais Costa Silva

The technology and the knowledge about the behavior of explosives and detonation accessories allowed to create new products for different situations by the restrictions imposed by the market. In a Brazilian underground copper mine the restriction occurred in the use of high grammage Det Cord in the development heading blasts perimeter holes. Enaex Brazil has developed Densiex UG™ (Low-Density Bulk Emulsion), a water-resistant bulk gassing emulsion with a density ranging from 0.60 to 0.90 g/cm³ to replace the high grammage Det Cord in blasts. That product is pumped in the same Mobile Manufacturing Unit (MMU) as Enaex Brazil's standard underground (UG) bulk emulsion. This product has a Lower Velocity of Detonation (VOD), vibration, and detonation pressure, which contributes to a better finishing of the drift, lower impact in the support structures, and lower generation on unstable rocks in the perimeter of the drift. This case aims to summarize the results of the work on the application of the Low-Density Bulk Emulsion in perimeter holes in an underground development gallery at an underground copper mine in Brazil. During this work, 10 horizontal drift blasts were performed using the Low-Density Bulk Emulsion, which presented an average density of 0.64 g/cm³, increasing safety, a 25% reduction in overbreak, a 23% reduction in scaling time, elimination of rework, and a saving of $135,000 per year for this business partner that immediately implemented this new product in all blasts at this mine.

Jan 21, 2025

By Dale S. Preece, Vanessa S. Berg

Shaped charges are being utilized in defense applications against a wider variety of targets including concrete, rock, and soil. This work was motivated by a heightened interest in characterizing the effect of shaped charge attack on brittle, non-homogenous materials, in particular, concrete damage and penetration predictions resulting from a TOW-2a conical shaped charge (CSC). This paper presents a multi-stage approach for accurately predicting the high explosive detonation and subsequent jet formation due to the collapse of shaped charge liner, the changes in jet length and diameter as a function of standoff distance, and the jet-target impact dynamics. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN to predict the shaped charge jet formation. 2-D finite difference Eulerian subgrids represent the explosive and casings components, while thin components like the liner are modeled with Shell subgrids. The Pugh, Eichelberger & Rostoker (PER) jetting theory option is invoked to obtain the jet and slug masses and associated velocities. The jetting data is post processed where the jet velocity gradient and jet mass is used to solve for the new jet length and diameter gradient at a desired standoff. The final computation involves a 2-D fully Lagrangian model in which the jet and velocity gradient is represented by a string of Lagrangian segments and the concrete target is defined as Lagrangian with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model. This model has a third invariant dependency that accounts for failure mechanisms in brittle materials.

Jan 1, 2004

By G. Walsh, M. T. Wild

In this paper the performance effects of linear shaped charges will be discussed. Different sized charges were tested and reviewed based on their performance used with a typical detonation method vs. detonation with a line wave generator. The goal of the project was to determine if the linear shaped charge had better performance with an ideally linear wave moving through it, verses a swept wave that is currently used. A line wave generator is a flexible sheet explosive formed into a triangular shape with holes placed in strategic places to cause a detonation wave to become linear across the width of the triangle. A standard linear shape charge with a detonator in the side of the charge was be detonated against a witness plate to get a standard depth of penetration. A second standard linear shape charge with a detonator connected to the top of a line wave generator, the line wave generator placed on top of the linear shape charge, was be detonated against a witness plate to get a comparison depth of penetration. All charges had a standoff 1.5 times the width of the cavity, allowing the data to be compared to the control charge. Computer modeling was intended to be used to predict the results from testing these designs in the field. The actual results were compared among themselves.

Jan 1, 2011

By C. E. Johnson, R. L. Bauer, E. M. Johnson

In industry, the strength of a blasting cap is often equated to the type of explosive it can detonate. Comparable cap strength is becoming less important as nearly all caps manufactured today can initiate high explosives, such as primasheet, with ease. Previous studies were conducted to assess the quantity of energy released by various detonators into the directional propulsion of the detonator’s casing. However, the question of how much of this propulsion energy is needed to initiate an explosive remains unanswered. This study will assess the fragmentation size and velocity needed to initiate a high explosive when they are not in direct contact. For this study, primasheet was used as the main charge as it is relatively insensitive and can be situated in different positions relative to the detonator. Electric, non-electric and electronic detonators were used to evaluate initiation potential. The primasheet is observed in response to being in contact with a detonator, and not in contact with the detonator at various distances and angles. This allowed the quantity of energy transferred into the primasheet to be observed and for the initiation of the sheet to be recorded using high-speed video. This study will report the energy necessary to initiate the primasheet at various distances and angles from the charge from a number of widely used, commercial, hot wire blasting caps.

Feb 6, 2023

By Tom Treleaven

The success of any blast is dependent on the accuracy of the blast design and the field controls used on the shot. This point cannot be over emphasized because when the geometry is not measured and/or field controls are not properly implemented, it can often have devastating effects on the final blast results. Thus drilling accuracy, tiont row burden control, explosive confinement, energy distribution, explosive selection, timing and structural geology become critical parameters in the design of successful blasts. Understanding the actual dynamics of the blast and why certain results were achieved is the fast step in optimizing a blast design. As stated by R. Frank Chiappetta, “Of all the blast monitoring systems available today, high speed videography still remains as the best stand alone instrumentation system for blast diagnostics.” Over the past years I have analyzed hundreds of blasts using either high-speed lowcams (500 frames per second) cameras or standard digital (30 frames per second). These analyses confirm, without a doubt, that shot geometry, in combination with structural geology, is the most important factor in overall blast results. Drilling accuracy is the single most important component in efficient blasting. Having equal mass associated with an equivalent energy is the basis in which blasts are designed. When drilling inaccuracy or borehole deviation occurs, not only is the energy unevenly distributed, but the basis of all design calculations becomes invalid. Over the past several years, quarry and mining operations have employed the use of boretracking measuring devices to measure borehole deviation and hole toe locations. In cases of operations using top hammer drills, it was discovered that the amount of deviation was significant and far greater than they believed they had. Set up error, improper drilling techniques and bit wear were some of the contributing factors. Through video anaysis of boretracked blasts, blast results were directly linked to drilling ..accuracy. The comparisons here took into account blast design, energy factors and hole sequencing.

Jan 1, 2000

By Anderson Meireles, Leonardo Soares Chaves, Raul Carretero Hoz, Carlos Eduardo Soares Feliciano, Renato Jacome Costa

The large iron deposits in the northern region of Brazil located in the Amazon Craton have in common the presence of natural cavities. These cavities primarily occur in the upper layer of the ore body, formed above hematite mineralization. Their origin remains a topic of debate, often associated with hydrothermal drainage processes and erosive evolution. Over time, these cavities have become integral to the local environment, each contributing to the regional ecosystem of fauna, flora, and the significance of speleothems found within them. Managing these cavities poses a significant challenge for iron mines in the area. On one hand, they must preserve the cavities from anthropogenic actions, while simultaneously handling heavy equipment and large volumes. In 2023, the development of the mine took place towards the cavity under study, revealing systematic deviations in vibrations recorded during nearby detonations as the blasting got nearer. To address this, a work plan was put in place, emphasizing a straightforward approach: constructing lithology-specific vibration models, defining charge abacuses, and optimizing timing to reduce charge amplification. Implementing this methodology significantly improved adherence to the vibration limit, resulting in an around 50% reduction in standard error. This paper presents the consolidated work that allowed mining activities to continue in the area through controlled blasting, effectively mitigating potential anthropogenic damage in sensitive areas.

Jan 21, 2025

By Lon Santis, Bill Evans, John Tatom

Debris data from the Department of Defense Explosives Safety Board’s Project ESKIMORE full-scale explosives event test program are compared to quantity-distance (Q/D) standards and quantitative risk analysis (QRA) methods. The ESKIMORE test program involved quantities of explosives ranging from 1,000 to 60,000 pounds detonated in typically sized structures made of metal and concrete. Debris from these events was extensively surveyed and catalogued. The debris patterns from these events show varying degrees of directionality normal to the walls of the structures. These density patterns are overlaid an existing explosives storage site that is comparable to the test conditions. Analysis of the debris patterns in relation to Q/D standards shows that exposures located beyond the Q/D arc but along the normal to walls of potential explosion sites (PES) may have much higher debris density than exposures at the same distance on the corners of the same PES. Analysis of the debris patterns shows that predicted patterns using the QRA tool IMESAFR v2.0 closely match actual patterns. Additionally, IMESAFR based QRA methods are able to quantify the different risk levels of being exposed along the wall’s normal as compared to being exposed on the structure’s corner. Methods and decision making criteria to mitigate risk based on the directionality of PES debris are presented. Copyright ©

Jan 1, 2015

By Tristan Worsey, John Henchion, Nathan Rouse, Yannick Lauras

"This paper presents an approach used to plan and evaluate drill and blast trials for a mine that currently mechanically excavates in-situ rock. The document presents the approach used to plan the trials, the key performance indicators (KPIs) that were necessary to evaluate the mining methods, the test matrix used during the trials, and the results of the trials. The trials, which occurred as part of an overall drill to mill optimization project at this site, helped to evaluate various blast designs using fragmentation results,drilling and blasting costs, and downstream costs. This project was unique in that (1) drill and blast methods were trialed on multiple rock types and various bench heights using a range of blasthole diameters and powder factors and (2) the load and haul costs were evaluated using a range of loading equipment, from 66 tonne (73 ton) excavators up to 250 tonne (276 ton) excavators. A ten year net cost financial evaluation of the material extraction alternatives was also prepared for the site management. Ultimately, the process of evaluating the drill and blast trials helped the management decide whether to continue extracting using mechanical methods or to introduce drill and blast methods to extract the rock."

Jan 1, 2017

By P D. Katsabanis, L Liu

Numerical modelling of fragmentation and throw is used to provide information on practical blast design parameters. The function of airdecking and its practical implications, the importance of the initiation point and aspect ratio of cratering charges and the timing between adjacent blastholes are investigated. Accuracy requirements for detonators are discussed with emphasis placed on the volume and fragmentation of the blasted rock, and compared to experimental results. Practical guidelines which have been based on intuition are examined using the model. Some of the predictions have been tested and correlate well with experimental results, obtained in the laboratory. Findings show that a minimum airdeck length is needed to realize any benefit from the application of airdecking in production blasting while the process can enhance the shock energy provided by non-ideal explosives significantly, bottom initiation of charges is beneficial to fragmentation and the aspect ratio for cratering charges can exceed the traditionally accepted ratio of 6. Regarding timing, in the ease of cratering charges, true simultaneous initiation shows beneficial results for the volume of blasted rock; however the accuracy required for practical detonators is very high. Fragmentation improves after a certain delay time while the optimum can be achieved at a range of delays. Timing affects muckpile shape; however it appears that subtle differences in delay times do not have a significant effect.

Jan 1, 1997

By B Mohanty

Full-face blasting rounds have been used to excavate a 4.6-mdiameter shaft at Atomic Energy of Canada Limited's Underground Research Laboratory near Pinawa, Manitoba. Both standard pyrotechnic delay detonators and the newly developed electronic delay detonators (EDD) were used on the project. The full-face blasting technique, employing 89-mm-diameter relief holes and 38-mm diameter blast holes, NG-based explosives, and the regular long period delay detonators, has been standard practice at the site, giving excellent wall control and fragmentation results. The comparison blasts using pyrotechnic detonators and EDDs were carried out to test the operational logistics, timing accuracy and blast results obtained with the latter. The long period pyrotechnic delays ranged from O to 18, with the nominal delay varying between 350 ms and 800 ms. The EDD blasts used the same number of periods, with the respective delay interval between successive periods set precisely at 190 ms and 210 ms for the two blasts. Based on a broad range of critically assessed parameters, the EDD blast results proved to be signficantly superior to those obtained with regular pyrotechnic detonators. The results have been analyzed in detail and the relative merits of the two delay systems have been determined. Alternative designs to derive maximum benefits from EDDs in shaft and tunnel blasts have also been suggested.

Jan 1, 1990

By Frank Hammelmann, Peter Reinders

This paper briefly describes the past history of blast management. A modern blast management suite is then presented which demonstrates the current capability of the functional link between an electronic blasting system and blast design software. Finally, we look at the potential of tomorrow’s fully integrated blast management systems. From the first time blasting was introduced in mining as part of the production process, blasting technology and blast management have been interconnected. Over the past decades we have gained more recent experience with the new electronic blasting systems in mining, quarrying and construction. To start, the primary focus of electronic blasting was to increase timing accuracy. However, since then the technology has gradually developed, broadened and opened up new possibilities, including impressive flexibility in blast design and full in-situ verification of system functionality. To support this capability, modern electronic blasting systems are specifically designed to facilitate full two-way transfer of information between the office-based blast management software and field-hardened equipment. Blast management systems now comprise a suite of expert systems for planning, documentation, analysis, measurement and prediction of blasts. Within this blast management suite, the blast design software allows the transfer of the blast design information from a PC directly to the hardware of the electronic blasting system. The future development of this technology holds huge potential for the blasting industry.

Jan 1, 2004

By V. A. Akinbinua

This work is intended to examine the relationship between rock fragments produced during compression tests using a soft testing machine, e.g. hydraulic press (the machine used in this work is Amlser rock testing machine), and the rock fragments size distribution produced by fragmentation of the same rock through application of explosive. The rocks tested are fine grained marble, medium grained tonalite and fine-medium grained granite, medium grained norite and medium grained gabbro. The rocks types are prepared according to ISRM methods to be tested for strength determination. The rocks are loaded at constant load until failure. The fragments resulting from the failure of each of the rocks types are collected for size characterization by sieve analysis. The same rocks tested under soft testing machine are also prepared into blocks of dimension 150 mm length x 100 mm width x 100 mm height for blasting by explosive application. Each block of the different rocks are drilled through with an 8 mm diameter drill to a depth of 80 mm. Each of the holes on the blocks is spaced from each other at 44.7 mm and with a burden of 28 mm. The holes therefore formed a rectangular blasting pattern. Each of the holes was charged with a 720 mg electronic detonator and fired instantaneously inside a cylindrical blasting chamber. After each shot, the fragments are collected for size characterization. The sizes distributions from blasting are compared with sizes distributions resulting from rock testing using the parameter Xc of the Rosin-Rammler distribution function (RR) and 75% cumulative percentage passing. The analysis and finding from this work is presented in this paper.

Jan 1, 2014

By Michael David Wilkins, Paul N. Worsey

Little research has been published on stemming blast holes, particularly what happens during the process. Previous work has concentrated on the performance of the inert material to find the best way to seal the hole and retain the explosive energy, at the exclusion of determining what happens during the loading and stemming process.

Jan 1, 1998

By J S. Kuszmaul

"A computational model of rock blasting is being developed to examine the blasting problems associated with in situ oil shale processing. This model, however, will also be useful as a design tool for the traditional problems in rock blasting. The model includes fundamental treatment of both shock-wave propagation and the accumulation of brittle fracture in the rock. As a result, the model accurately predicts the degree and extent of fracturing as functions of design parameters. The model has proven useful for making parametric studies and for evaluation of alternate blast designs. This paper demonstrates the use of the numerical model to simulate the fracturing induced by the detonation of a vertical explosive column near a bench. The fracturing induced by three differentexplosives indicate that (in the chosen geometry) the most efficient breakage is done by a column of ammonium nitrate and fuel oil mixture (ANFO) used with a toe charge of aluminized ANFO. There was too much unfractured rock left when ANFO was used alone; aluminized ANFO used for the entire explosive column caused excessive fracturing. A final case involves ANFO used alone to fracture a different rock type. This case points out that in a different rock type, the ANFO will not leave excessive unfractured rock."

Jan 1, 1987

By Robert C. Brown

During a research period lasting over three years, a vast number of seismograms were collected and analyzed. From this data, other than obtaining a host of new information pertaining to the effects of surface mine blast on underground mines, it was found that by mounting seismograph velocity transducers at the center of crosscuts in underground mines, seismograms can be obtained which give fairly accurate information about the maximum levels of vibration, and the associated Of stresses and strains, misfiring of blast holes, delay accuracy and delay overlap. The technique of analysis is a simple one; it involves matching of the frequency of wave or wave groups with the shot card information such as rows of holes, number of holes and the cumulative milliseconds of delays used in the blast holes. Any discrepancy that might exist between the frequency of waves and the expected cumulative millisecond delay for a given row or hole eventually will show up as a mismatch in the analysis. This simple technique enables the seismographer to be involved not only in the monitoring of blast peak vibration, but also in making recommendations as to the choice of millisecond delays, reducing the possibility of delay overlaps and reducing the hazards of blast hole cutoffs.

Jan 1, 1980

By R. K. Wharton

The paper reviews the development of European harmonised standards for fireworks, recent major incidents involving the bulk storage of fireworks which led to research funded by the European Commission, progress with the forthcoming European Regulation on pyrotechnics and potential issues relating to the certification of products within the scope of the new Regulation.

Jan 1, 2005

By Rajesh Sonkar, Sanjeev Kumar

The deployment of Dragline machines in opencast coal projects involves huge capital expenditure as well as operating costs. The mine operators always endeavor to ensure smooth excavation of material by the Dragline machines while meeting the major objectives of safety, minimal disturbance to environment and optimal operating costs. Optimization of fragmentation through well designed blasts is fundamental in meeting part of the objectives is good fragmentation of rock or mineral proposed to be lifted by the Dragline machine. If the overburden lying over mineral is not properly fragmented, it may result in formation of ‘Toe’ the removal of which is the most arduous task in opencast coal mines. The mine operators always endeavor to achieve best possible results in blasting to ensure smooth operation of the high cost Dragline Machine. However, despite continuous efforts by the blasting engineers involved in bench blasting for the machine, the formation of ‘Toe’ is an ever nagging problem faced in large opencast coal projects eventually reducing the overall operational efficiency of mining.

Jan 1, 2011

By Amos Bryant, Jesse Davis

This paper compares the predictions of the latest Institute of Makers of Explosives Safety Analysis for Risk (IMESAFR) model versus physical test data recovered from ISO-1 and ISO-2 tests in Woomera, SA. ISO-1 testing included placing 1054 kg (2324 lbs) of ANFO (ammonium nitrate-fuel oil) inside an ISO container on a flat bed truck. ISO-2 testing was identical except the NEW was 4000 kg (8818 lbs). The IMESAFR predictions are based on model runs using the best match available to the actual donor type involved in the test. This type of debris analysis is not the standard output of IMESAFR, as the program is designed to assess the probability of human fatality. However, all of the IMESAFR predictions presented were obtained from the use of the actual model equations and algorithms without adjustment. Test results from ISO-1 and ISO-2 will be presented as well as findings from the comparison between model results and actual explosive results from the ISO testing efforts.

Jan 1, 2010

By Rufus Flinchum

Two of the most critical concerns a blaster faces today are airblast and flyrock. Airblast, sometimes called noise or overpressure, can cause damage to neighboring structures, especially windows. It also is the cause for many vibration complaints. The human sense of hearing is often more acute to identifying source than the sense of touch. When a blast occurs, the airblast is what identifies the event. The vibration that may be felt is then associated with the airblast. Vibrations of greater magnitude, such as passing trucks or construction work on the house, go unnoticed because their sounds are familiar or expected. Flyrock is the number one killer and cause of damage. Elasting laws provide limits for these two concerns. Failure to comply may result in fines, closing of the operation, and even prison. Airblast and flyrock originate from two distinct areas, the open face and the bench surface. Each of these areas is addressed in the detailed proven procedures that follow, and if used by the blaster in conjunction with his own blasting knowledge, a sound blasting plan can be developed to minimize the occurrence of airblast and flyrock.

Jan 1, 1992